Variable device for bulk material distribution with rotary chute having variable angle of inclination

ABSTRACT

A device for distributing bulk materials includes a suspension rotor is mounted in a support frame which is capable of rotating about a substantially vertical axis of rotation. A chute is suspended to the suspension rotor and is tiltable about a substantially horizontal tilt axis. A first motor is capable of rotating the suspension rotor about its axis of rotation in a first direction, and a tilt controlling motor mounted in the support frame is capable of rotating about a substantially vertical axis of rotation. A tilting mechanism is also connected between the chute and the tilt controlling rotor, while a first braking device exerts a braking moment on the tilt controlling motor. A first control device controls the angle of inclination of the chute by controlled braking of the tilt controlling rotor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is entitled to the benefit of and incorporates byreference in their entireties essential subject matter disclosed inInternational Application No. PCT/EP01/09830 filed on Aug. 27, 2001 andLuxembourg Patent Application No. 90642 filed on Sep. 20, 2000.

FIELD OF THE INVENTION

The present invention relates to a device for distributing bulkmaterials with a rotary chute with a variable angle of inclination.

More specifically, it relates to such a device comprising a supportframe, a chute for distributing bulk materials, a suspension rotor and atilt controlling rotor, as well as a tilting mechanism. The chute issuspended to the suspension rotor so as to be tiltable about asubstantially horizontal tilt axis. The tilting mechanism is connectedbetween the chute and the tilt controlling rotor in order to transform adifferential rotation of the suspension rotor and of the tiltcontrolling rotor into a variation of the angle of inclination of thechute between two extreme positions.

BACKGROUND OF THE INVENTION

Such a device is known for example from U.S. Pat. No. 3,693,812. In thisdevice, both rotors are rotated via a planetary gear box. From thisplanetary gear box, emerge: (1) a main input shaft; (2) a secondaryinput shaft; (3) a first output shaft, called rotary shaft hereafter;and (4) a second output shaft, called tilt controlling shaft hereafter.The main input shaft is rotated by a driving motor. A demultiplyingmechanism connects the main input shaft to the rotary shaft. The latterpenetrates into the support frame where it engages by means of a pinionwith a toothed ring of the suspension rotor. The tilt controlling shaftitself also penetrates into the support frame, where it engages by meansof a pinion with a toothed ring of the tilt controlling rotor. Theplanetary gear box further comprises: a horizontal annular toothedwheel, which engages at its external perimeter with a pinion of therotary shaft; a solar wheel which is borne by the secondary input shaft;at least two satellite pinions, which engage with the internal perimeterof the annular toothed wheel and the solar wheel; and a satellite pinioncarrier, which engages with a toothed wheel of the tilt controllingshaft. These gears are dimensioned so that both output shafts have thesame speed of rotation when the secondary input shaft is not rotating. Acontrol motor with a reversible direction of rotation is connected tothe secondary input shaft of the planetary gear. By driving this controlmotor in a first direction, the chute is tilted in a first direction andby driving it in the reverse direction, the chute is tilted in thereverse direction. The speed of rotation of the control motor determinesthe tilt speed of the chute, regardless of the speed of rotation of thechute. By blocking the secondary input shaft by means of a brake, astrictly constant angle of inclination is provided for the rotatingchute.

It will be noted that this planetary gear box is a key piece ofequipment of the device for distributing bulk materials. This is aspecial design which accounts for a large portion of the price of thedevice. Further, in order to remain operational when the driving unitrequires servicing or a major repair, a complete planetary gear boxshould be kept in reserve.

OBJECTS AND SUMMARY OF THE INVENTION

The object of the present invention is to provide a device fordistributing bulk materials of the type described above, with a simplerdriving mechanism, notably causing less problems in the case of majorservicing or repairs.

According to the invention, this object is achieved by a device fordistributing bulk materials comprising—in a known way per se—a supportframe, a chute for distributing the bulk materials, a suspension rotor,a tilt controlling rotor and a tilting mechanism. Both rotors aremounted on the support frame so that they are both capable of rotatingabout a substantially vertical axis of rotation. The chute is suspendedto the suspension rotor, so as to be tiltable about a substantiallyhorizontal tilting axis. The suspension rotor (and consequently thechute) can be driven with a first motor in a first direction about itsaxis of rotation. The tilting mechanism is connected between the chuteand the tilt controlling rotor, in order to transform a differentialrotation of the suspension rotor and of the tilt controlling rotor intoa variation of the angle of inclination of the chute between two extremepositions. According to a first aspect of the present invention, thechute is balanced in order to return to a first of its two extremepositions, while accelerating the tilt controlling rotor via the tiltingmechanism in the direction of rotation of the suspension rotor. In thisembodiment, a first braking device is associated with the tiltcontrolling rotor so that it is capable of exerting a braking moment onthe tilt controlling rotor. With this first braking device is associateda first control device which allows the tilting of the chute to becontrolled by controlling the braking moment applied to the tiltcontrolling rotor, when the suspension rotor is driven in the firstdirection of rotation. If the braking moment exerted on the tiltcontrolling rotor is equal to the moment required for maintaining thechute in an equilibrium position, the chute remains fixed in tilt. Ifthe braking moment exerted on the tilt controlling rotor is larger thanthe moment required for maintaining the chute in the equilibriumposition, the chute moves away from its first extreme position ofinclination. If the braking motor exerted by the tilt controlling rotoris less than the moment required for maintaining the chute in theequilibrium position, the chute moves closer to its first extremeposition of inclination, because its special balancing causes anacceleration of the tilt controlling rotor relatively to the suspensionrotor. In the three cases, the first motor must of course develop adriving moment which is larger than the braking moment of the tiltcontrolling rotor, while providing a substantially constant speed ofrotation. It remains to be noted that for providing the balance of thechute which ensures its return to a first of its two extreme positions,it is possible to either involve the weight of the chute exclusively orresort to counterweights or springs or other components capable ofstoring potential energy when the chute is tilted in one direction andof releasing it when the chute should be tilted in the reversedirection. As a conclusion, by associating the tilt controlling rotorwith a simple braking device having a controllable braking moment, theangle of inclination of the chute as well as its tilting speed can becontrolled, when the latter rotates in a first direction.

In order to provide rotation of the chute with a strictly constant angleof inclination without having to continually brake the tilt controllingrotor, a clutch transmission mechanism can be connected between thesuspension rotor and the tilt controlling rotor. In the engagedposition, this mechanism makes both rotors interdependent in rotation,i.e. provides a same speed or rotation for both rotors, whereas in thedisengaged position of the clutch, the mechanism provides acceleration,deceleration of one rotor relatively to the other, respectively. Inother words, after having set a particular angle of inclination of thechute by varying the braking moment of the tilt controlling rotor withthe transmission mechanism disengaged, the transmission mechanism can beengaged in order to mechanically set the angular shift of both rotorsand thus provide a strictly constant angle of inclination of the chutewithout having to spend any energy for this purpose.

If the intention is not to be limited to one direction of rotation forthe chute or to be able to adjust the angle of inclination of the chutewhen the latter is rotationally fixed, a second motor must be associatedwith the tilt controlling rotor so as to be capable of driving thelatter about its axis of rotation in a second direction of rotation, anda second braking device must be associated with the suspension rotor sothat as to be capable of exerting a braking moment on the suspensionrotor. A control device which is associated with the second brakingdevice, provides in this case control over the variation of the angle ofinclination of the chute rotating in the second direction, by changingthe braking moment of the suspension rotor. In order to provide astrictly constant angle of inclination of the chute without having tospend energy for this purpose, one will advantageously resort to thegear transmission mechanism described earlier. It remains to be notedthat the inclination of the chute may also be changed without driving itinto rotation. For this purpose, the suspension rotor is blocked inrotation via the second braking device and the tilt of the chute iscontrolled in a first direction by having the tilt controlling rotordriven by the second motor and in a second direction by braking the tiltcontrolling rotor via the first braking device, taking advantage of thefact that the balance of the chute makes it return to a first of twoextreme positions.

In order to guarantee a substantially constant speed of rotation of thechute in said second direction of rotation, when the angle ofinclination of the chute is varied by braking the suspension rotor, avariable speed drive must be associated with the second motor. With acontrol device associated with the variable speed drive, the desiredspeed of rotation of the suspension rotor may then be provided, whereaswith the second control device controlling the braking moment of thesuspension rotor, the desired tilting speed of the chute can beprovided. Alternatively, the speed of rotation of the chute can beimposed via the second braking device and a control device can beassociated with the variable speed drive of the second motor, andprovide direct control over the tilting speed of the chute. It remainsto be noted that in both cases, the second motor with its variable speeddrive should be able to drive the tilt controlling rotor at a speed ofrotation higher and less than the desired speed of rotation for thechute.

In the above description, it is assumed that the chute is balanced sothat it returns to a first of its two extreme positions, whileaccelerating the tilt controlling rotor via the tilting mechanism in thedirection of rotation of the suspension rotor. If such balancing werenot possible, the device according to the invention should be equippedas follows. A first braking device is associated to the tilt controllingrotor so that it is capable of exerting a braking moment on the tiltcontrolling rotor. A second motor is associated with the tiltcontrolling rotor, so that it is capable of driving the latter about itsaxis in the first direction at a higher speed of rotation than thedesired speed of rotation for the chute. A second braking device isassociated with the suspension rotor so that it is capable of exerting abraking moment on the suspension rotor. A control device then allows thetilting of the chute to be controlled in a first direction, by drivingthe suspension rotor in the first direction and by controlled braking ofthe tilt controlling rotor by means of the first braking device, and ina second direction, by driving the tilt controlling rotor in the firstdirection, at a higher speed of rotation than the desired speed ofrotation for the chute, and by controlled braking of the suspensionrotor by means of the second braking device.

If, in the device of the above paragraph, the tilting mechanism is aperfectly self-blocking mechanism, i.e. no moment needs to be applied tosaid tilt controlling rotor in order to maintain the chute fixed intilt, then it is sufficient to rotate the suspension rotor and not tobrake the tilt controlling rotor in order to provide rotation of thechute with a strictly constant angle of inclination. If however thetilting mechanism is not perfectly self-blocking or if there is a riskthat wear and tear will destroy its self-blocking character, it is thenrecommended to equip the device with a transmission mechanism having aclutch as described earlier.

If the intention is not to be limited to only one direction of rotationfor the chute, the first motor needs to be able to drive the suspensionrotor in a second direction of rotation at the desired speed of rotationfor the chute, and the second motor should be able to drive the tiltcontrolling rotor in the second direction of rotation at a higher speedof rotation than the desired speed of rotation for the chute. In thiscase, the control device associated with the first braking device, withthe second braking device and with the second motor, must be able tocontrol the tilting of the chute: (a) in a first direction, by drivingthe tilt controlling rotor by means of the second motor in the seconddirection at a higher speed of rotation than the desired speed ofrotation for the chute and by controlled braking of the suspension rotorby means of the second braking device; and (b) in a second direction, bydriving the suspension rotor in the second direction and by controlledbraking of the tilt controlling rotor by means of the first brakingdevice. It remains to be noted that in this device, the inclination ofthe chute may also be changed without driving it into rotation. For thispurpose, the rotating suspension rotor is blocked via the second brakingdevice and the tilt of the chute is controlled, in a first direction, byhaving the tilt controlling rotor driven by the second motor in a firstdirection, in a second direction, by having the tilt controlling rotordriven by the second motor in a second direction.

In order to guarantee with the device described in the above paragraph,a substantially constant speed of rotation of the chute when the angleof inclination is varied by braking the suspension rotor, a variablespeed drive should be associated with the second motor. A control deviceassociated with the variable speed drive is then able to provide thedesired speed of rotation of the suspension rotor, whereas the secondcontrol device controlling the braking moment of the suspension rotor,is able to provide the desired tilting speed of the chute.Alternatively, the speed of rotation of the chute can be imposed via thesecond braking device and a control device can be associated with thevariable speed drive of the second motor, and then provide directcontrol over the tilting speed of the chute. It remains to be noted thatthe second motor with its variable speed drive, needs to be able todrive the tilt controlling rotor at a higher speed of rotation than thedesired speed of rotation for the chute.

It is important to note that the braking device used in a device such asthe one described above, for braking the tilt controlling rotor or thesuspension rotor may for example be a mechanical, hydraulic, magnetic orelectromagnetic brake. In a preferred embodiment of a device accordingto the invention, the first motor and the second, braking device, thesecond motor and the first braking device respectively, however form aunit comprising a rotating electric machine powered by an electricalcircuit so that it is capable of operating in motor mode to develop adriving torque and in a generator mode to develop a braking torque, thisin at least one direction of rotation. In other words, the first drivingmotor, the second driving motor respectively, also fulfills the functionof an electric brake. It remains to be noted that this solution not onlysimplifies the construction of the device (no need to provide a separatebrake) but it is also of interest from the point of view of the energybalance of the device. Indeed, the rotating electric machine operatingin generator mode transforms braking power into electrical power, whichit injects into the mains electric power supply network. This electricalpower is then used for at least partly compensating the electrical powerthat the rotating electric machine operating in the motor mode absorbsin order to overcome the braking moment developed for controlling theangle of inclination of the chute.

In a preferred embodiment of a device according to the invention, therotating electric machine is for example an electric motor equipped witha speed reducer, and the electrical circuit is a static frequencyconverter. These are standard cheap pieces of equipment and theirreplacement in the event of machine breakage will normally not be aproblem.

It remains to be noted that the devices for controlling the tilt of thechute as mentioned above, may comprise different means for sensing theinclination of the chute. In a first embodiment, a first angle sensor isused which senses the angular position of the suspension rotor, a secondangle sensor sensing the angular position of the tilt controlling rotorand computation means for computing the relative angular position ofboth rotors, and for inferring therefrom the tilt of the chute. However,better accuracy of the control device is provided when a differentialangle sensor is used which directly senses the relative angular positionof both motors. This accuracy may further be enhanced by connecting adifferential measurement mechanism between both motors. Such a mechanismcomprises e.g. a first input shaft, a second input shaft and an outputshaft. The first input shaft is rotated by the suspension rotor and thesecond input shaft is rotated by the tilt controlling rotor. Thisdifferential measurement mechanism is dimensioned so that the outputshaft is rotationally fixed when both rotors have the same speed ofrotation and so that it reproduces the angle of inclination of the chutein a rotationally fixed reference system. A single angle sensor thensenses the angular position of the output shaft of the differentialmeasurement mechanism and thus detects the inclination of the chute in arotationally fixed reference system. The tilt controlling device mayalso comprise a sensor for the inclination of the chute, rotating withthe chute. In this case, a transmitter is associated with therotationally mobile inclination sensor and at least one receiver ismounted in the rotationally fixed support frame. In this way, it isknown how to measure the tilt of the chute directly in its rotatingreferential.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and characteristics of the invention will become apparentfrom the detailed description of a few advantageous embodiments shownbelow, by way of illustration, with reference to the appended drawings:

FIG. 1 shows a planar view of a device for distributing bulk materialswith a rotary chute having a variable angle of inclination according tothe invention;

FIG. 2 shows a longitudinal sectional view through the device of FIG. 1,the upper portion being a sectional view along the sectional line A—A ofFIG. 1; the lower portion being a sectional view along the sectionalline B—B of FIG. 1;

FIG. 3 is an elevational view of a detail which is identified by arrow 3in FIG. 2;

FIG. 4 is a longitudinal sectional view similar to that of FIG. 2,through a first alternative embodiment of a device for distributing bulkmaterials with a rotary chute having a variable angle of inclinationaccording to the invention;

FIG. 5 is a longitudinal sectional view similar to that of FIG. 2,through a second alternative embodiment of a device for distributingbulk materials with a rotary chute having a variable angle ofinclination according to the invention; and

FIG. 6 is a transverse sectional view, the sectional line of which isidentified by arrows 6—6 in FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

In the figures, the same reference symbols refer to identical or similarcomponents.

The device for distributing bulk materials 10 shown in FIGS. 1, 2, 4 and5, is more particularly intended to be part of a charging device of ashaft furnace, such as a blast furnace for example. It comprises anexternal frame 12, which is provided with a fixed feeding sleeve 14defining a vertical feeding channel 16. A suspension rotor 18 issuspended in the external frame 12 by means of a large diameter ballbearing 20. This suspension rotor 18 comprises a cylindrical bodyprovided at its lower end with a horizontal flange 24, which acts as ascreen between the inside of the frame 12 and the inside of the furnace.A second rotor 28, called the tilt controlling rotor 28, surrounds thesuspension rotor 18 and is suspended in the external frame 12 by meansof a large diameter ball bearing 26, in order to have its axis ofrotation substantially coaxial to the axis of rotation of the suspensionrotor 18.

Reference symbol 32 refers to a distribution chute for bulk materialspoured in through the feeding channel 16. This chute 32 comprises twoside suspension arms 34 and 34′, by means of which it is suspended tothe suspension rotor 18. With a tilting mechanism actuated by the tiltcontrolling rotor 28, the chute 32 can be tilted about a substantiallyhorizontal tilt axis. In the illustrated device, this tilting mechanismcomprises per suspension arm 34, 34′ of the chute 32, a suspensionmechanism 36, 36′ borne by the suspension rotor 20. Each of both ofthese suspension mechanisms 36, 36′, comprises a vertical input shaft38, 38′, an internal gear system (not shown) and a horizontal suspensionpin 40,40′. Both side suspension arms 34, 34′ of the chute 32.arecoupled with suspension pins 40,40′ and the latter define asubstantially horizontal tilt axis for the chute 32. The vertical inputshaft 38, 38′ of each of both suspension mechanisms 36, 36′ is equippedwith a pinion which engages with a toothed crown 43 of the tiltcontrolling rotor 28. The internal gear system transforms a rotation ofthe vertical input shaft 38, 38′ into a rotation of the suspension pin40,40′. It will be noted that both suspension mechanisms 36 and 36′should be symmetrical with respect to the middle plane of the chute 32,i.e. a rotation in the same direction as the input shaft 38, 38′, shouldresult in a rotation in opposite directions of both suspension pins40,40′.

It is important to note that other tilting mechanisms connected to thechute and actuated by the tilt controlling rotor are also known. Thus,U.S. Pat. No. 4,941,792 for example proposes the use as a tiltingmechanism, respectively of a forked tilting lever connected between bothpins and the tilt controlling rotor, or of a toothed ring segment whichcooperates with a toothed sector interdependent with one of both of thepins of the chute. U.S. Pat. No. 5,002,806 proposes the connection ofthe rotor by means of a rod with spherical joints, with a leverconnected to one of the pins of the chute. Other tilting mechanisms arealso known from WO95/21072, U.S. Pat. No. 4,368,813, U.S. Pat. No.3,814,403 and U.S. Pat. No. 3,766,868.

Reference symbol 50 refers to a first casing mounted on the supportframe 12. This casing 50 contains a vertical shaft 54, called a rotationshaft 54 hereafter, which is connected through a angular geartransmission mechanism 52 to a horizontal output shaft 56. The upper endof the rotary shaft 54 is coupled via a mechanical reducer 58 with anelectric motor 60. The lower end of the rotary shaft 54 sealably emergesout through the base plate of the casing 50 and is provided with apinion 62 which engages with a toothed crown 64 of the suspension rotor18. It remains to be noted that the support frame 12 is provided with aport 66 for the passage of the pinion 62, which is sealably closed bythe base plate of the casing 50. Reference symbol 70 refers to a secondcasing mounted on the support frame 12. This casing 70 contains avertical shaft 74, hereafter called the tilt controlling shaft 74 whichis connected by a angular gear transmission mechanism 72 to a horizontalinput shaft 76. The upper end of the rotary shaft 74 is coupled via amechanical reducer 78 with an electric motor 80. The lower end of thetilt controlling shaft 74 sealably emerges out through the base plate ofthe casing 70 and is provided with a pinion 82 which engages with atoothed crown 84 of the control rotor 26. It remains to be noted thatthe support frame 12 is also provided with a port 86 for the passage ofthe pinion 82, which is sealably closed by the base plate of the casing70. The horizontal output shaft 56 of the casing 50 and the horizontalinput shaft 76 of the casing 70 are coupled with each other by means ofa clutch 90. When the clutch 90 is in the engaged position, both rotors18, 28 are interdependent in rotation, i.e. it is impossible toaccelerate or decelerate one of the rotors 18, 28 relatively to theother. Further, the different gear ratios are dimensioned in such a waythat the speeds of rotation of both rotors 18, 28 are strictly identicalin this case. In order to accelerate or decelerate one of the rotors 18,28 with respect to the other, the clutch must therefore be disengaged90.

The reference symbol 100 globally refers to a control system controllingthe device for distributing bulk materials 10. This control system 100comprises a control central unit 102 comprising for example aprogrammable controller, which controls the electric motor 60 via afirst variable speed drive 104 and the electric motor 80 via a secondvariable speed drive 106. As feedback signals, the control central unit102 receives signals from two angle sensors 108 and 110. The anglesensor 108 senses via a gear 112 the angular position of the rotaryshaft 54 consequently that of the tilt controlling rotor 28. By means ofthe signal from the angle sensor 108, the central unit 102 computes theinstantaneous speed of rotation of the chute 32, as well as itsposition. On the; basis of the signal from both angle sensors 108 and110, the central unit 102 computes the inclination of the chute and theinstantaneous tilting speed of the chute 32. A set point unit 116enables set values to be entered into the control central unit 102 asregards notably the speed of rotation, the inclination and the tiltingspeed of the chute 32.

The operation of the device for distributing bulk materials 10 will nowbe described in more detail.

First of all, let us assume that the chute 32 is balanced so that it iscapable of tilting under the effect of it own weight in a quasi-verticalposition (i.e. in a position at which its angle of inclination, asmeasured with respect to the vertical, is minimal), and that the tiltingmechanism is dimensioned so that it is capable of respectivelyaccelerating the tilt controlling rotor in the direction of the arrow120 and the suspension rotor in the direction of the arrow 120′, whenthe chute 32 returns under the effect of its own weight to a position ofminimal inclination this notably means that a moment must be applied tothe tilt controlling rotor 28 in order to maintain the latter inequilibrium for a given angle of inclination. Let us also assume thatthe chute 32 should be rotated at speed N in the direction of the arrow120. To increase the angle of inclination of the chute 32 as measuredwith respect to the vertical, the variable speed drive 10106 has theelectric motor 80 operate as a generator which imposes a braking momentto the tilt controlling rotor 28, whereas the motor 60 drives thesuspension rotor 18 at speed N in the direction of the arrow 120.Indeed, if the braking moment exerted by tilt controlling rotor becomesgreater than the moment required for maintaining the chute in theequilibrium position, the tilt controlling rotor 28 decelerates withrespect to the suspension rotor and the angle of inclination of thechute 32 as measured with respect to the vertical, increases. The morethe braking moment exerted by the tilt controlling rotor 28 exceeds theequilibrium moment of the chute 32, the higher the deceleration of thetilt controlling rotor 28 with respect to the suspension rotor 18 andthe faster the tilting speed of the chute 32. Of course, it is motor 60which drives the suspension rotor 18, which must provide the requiredpower for overcoming the braking moment applied on the tilt controllingrotor 28 in order to decelerate the latter. This power is partlycompensated by the electrical power which the variable speed drive 10,106 injects into the mains electrical power supply network, when themotor 80 operates as a generator for generating the braking moment ofthe tilt controlling rotor 28. If the intention is to maintain the chute32 in rotation at speed N in the direction of the arrow 120 with aconstant angle of inclination, the braking moment of the motor 80 mustbe set by means of the variable speed drive 106 so that the speed ofrotation of the tilt controlling rotor 28 is substantially identical tothe speed of rotation N of the suspension rotor 18. When the speeds ofrotation of both rotors 18, 28 are quasi identical, the clutch 90 isengaged. From this moment, both rotors 18, 28 are interdependent inrotation and rotate at the same speed. The angle of inclination of thechute 32 is frozen at its value at the time of the engagement. Motor 80has no longer to develop a braking torque, it is capable of consequentlyrotate idly. As a result the motor 60 does no longer need to overcomethe braking moment of the tilt controlling rotor 28, which means thatits absorbed power is considerably reduced. To reduce once again theinclination of the chute 32 with respect to the vertical, the clutch 90is simply disengaged. The tilt controlling rotor 28 undergoes, by aparticular balance of the chute 32, an acceleration in the directions ofthe arrow 120, which reduces the delay of the tilt controlling rotor 28relatively to the suspension rotor 18. As a result, the angle ofinclination of the chute 32 with respect to the vertical, is againreduced. To control the tilting speed of the chute 32 towards itsposition of minimal angle of inclination, the control central unit 102may operate the electric motor 80 via the variable speed drive 106 as agenerator, which imposes a braking moment to the tilt controlling rotor.This braking moment should of course, remain smaller than the momentrequired for maintaining the chute 32 in its equilibrium position. Nowlet us assume that the chute 32 should rotate at speed N in the oppositedirection, i.e. in the direction of the arrow 120′. In order to increasethe angle of inclination of the chute 32 as measured with respect to thevertical, the variable speed drive 106 operates the electric motor 80 sothat it drives the tilt controlling rotor 28 at a speed N′>N in thedirection of the arrow 120′, and the variable speed drive 104 operatesthe electric motor 60 as a generator, which imposes a braking moment tothe suspension rotor 18. By means of the variable speed drive 106, thecontrol unit 102 controls the driving speed N′ of the tilt controllingrotor 28, in order to adjust the tilting speed of the chute 32 to thedesired value. By means of the variable speed drive 104, the controlunit 102 controls the motor 60 so that the speed of rotation of thesuspension rotor 18 remains substantially equal to the desired value N.Now, it is the motor 80 which must provide the power required forovercoming the braking moment applied to the suspension rotor 18 inorder to maintain the latter at the speed of rotation N. This power ispartly compensated by the electrical power that the variable speed drive104 injects into the mains electrical supply network, when motor 60operates as a generator for generating the braking moment of thesuspension rotor 18. If the intention is to maintain the chute 32rotating at speed N, in the direction of the arrow 120′, with a constantangle of inclination, the braking moment of the tilt rotor 28 should beset by means of the variable speed drive 106 until a zero tilting speedis obtained. A this moment, the speed of rotation of the tiltcontrolling rotor 28 is the same as the speed of rotation N of thesuspension rotor 18 and clutch 90 is engaged. Both rotors 18, 28 are nowinterdependent in rotation and rotate at the same speed. Motor 60 has noneed to develop a braking torque; it is capable of rotating idly. As aresult, motor 80 has no longer to overcome the braking moment of thesuspension rotor 18 which means that its absorbed power is considerablyreduced. It remains to be noted that if clutch 90 is engaged, the motor60 can be also used for driving the chute into rotation in the directionof the arrow 120′ at speed N. To again reduce the inclination of thechute 32 with respect to the vertical, clutch 90 is first disengaged.The suspension rotor 18 is subject, by the particular balance of thechute 32, to a driving moment in the directions of the arrow 120′, whichtends to accelerate it in the direction of rotation. By means of thevariable speed drive 104, the control unit 102 sets the braking momentof the suspension rotor 18 to adjust the speed of rotation of the chute32 to the desired value N. By means of the variable speed drive 106, thecontrol unit 102 sets the driving moment of the tilt controlling rotor28 in order to adjust the tilt speed of the chute 32 to the desiredvalue. If the speed of rotation N′ of the tilt controlling rotor 28 isless than the speed of rotation N of the suspension rotor 18, then theangle of inclination of the chute 32 with respect to the vertical isreduced.

If it is not required to drive the chute 32 into rotation in thedirection of the arrow 120′, the “motor 80” should only fulfill thefunction of a brake capable of exerting a braking moment on the tiltcontrolling rotor 28. In this event, of course, the motor 80 itsinverter 106 can be replaced with a mechanical, hydraulic, magnetic orelectromagnetic braking device, equipped with a suitable control devicefor controlling the variation of the angle of inclination of the chute32 by controlled braking of the tilt controlling rotor 28. It is thenpossible to do without the variable speed drive which powers the motor,provided that the latter is able to deliver a substantially constantspeed of rotation when it has to overcome a variable braking torque.

It remains to be noted that instead of balancing the chute so that ittilts under the effect of its own weight into a position at which itsangle of inclination as measured with respect to the vertical, isminimal, it might be also balanced so that it tilts under the effect ofa counterweight into a position at which its angle of inclination, asmeasured with respect to the vertical, is maximal. Finally, forbalancing the chute so that it returns into a position at which itsangle of inclination with respect to the vertical is either maximal orminimal, it is also possible to resort to springs or hydraulic cylinderscapable of storing potential energy when the chute is tilted in onedirection and of releasing it when the chute must be tilted in thereverse direction.

Let us now assume that the tilting mechanism is self-blocking, i.e. thatno moment needs to be applied to the tilting control motor in order tomaintain the angle of inclination of the chute constant. Again let usassume that the chute 32 should be rotated at speed N in the sense ofthe arrow 120. To increase the angle of inclination of the chute 32 asmeasured with respect to the vertical, the variable speed drive 106operates the electrical motor 80 as a generator, which imposes a brakingmoment to the tilt controlling rotor 28, whereas motor 60 drives thesuspension rotor 18 at speed N in the direction of the arrow 120.Indeed, if the braking moment exerted on the tilt controlling rotorbecomes larger than a certain value, the tilt controlling rotor 28decelerates relatively to the suspension rotor 18 and the angle ofinclination of the chute 32 as measured with respect to the vertical,increases. The larger the deceleration of the tilt controlling rotor 28with respect to the suspension rotor 18, the higher the tilting speed ofthe chute 32. Of course, it is motor 60 which must provide the powerrequired for overcoming the braking moment applied to the tiltcontrolling rotor 28 in order to decelerate the latter. This power ispartly compensated by the electrical power that the variable speed drive106 injects into the mains electrical power supply network, when motor80 operates as a generator for producing the braking moment of the tiltcontrolling rotor 28. To keep the chute 32 rotating at speed N in thedirection of the arrow 120 with a constant angle of inclination, it issufficient to operate the motor 80 under no load. However, if thetilting mechanism is not perfectly self-blocking for all the angles ofinclinations of the chute, it is then recommended to engage the clutch90 nonetheless, in order to provide a strictly constant angle ofinclination for the chute 32. To reduce the inclination of the chute 32with respect to the vertical, the variable speed drive 106 operates theelectric motor 80 so that it drives the tilt controlling rotor 28 at aspeed N′>N in the direction of the arrow 120, and the variable speeddrive 104 operates the electric motor 60 as a generator, which imposes abraking moment to the suspension rotor 18. By means of a variable speeddrive 104, the control unit 102 sets the braking moment of thesuspension rotor 18 in order to adjust the speed of rotation of thechute 32 to the desired value N. By means of the variable speed drive106, the control unit 102 sets the speed of rotation N′ of the tiltingrotor 28 in order to adjust the tilting speed of the chute 32 to thedesired value. Let us now assume that the tilting mechanism isself-blocking and that the chute 32 needs to be rotated at speed N inthe direction of the arrow 120′. To increase the inclination of thechute 32 with respect to the vertical, the variable speed drive 106operates the electric motor 80 so that it drives the tilt controllingrotor 28 at a speed N′>N in the direction of the arrow 120′, and thevariable speed drive 104 operates the electric motor 60 as a generatorwhich imposes a braking moment to the suspension rotor 18. By means ofthe variable speed drive 104, the control unit 102 sets the brakingmoment of the suspension rotor 18 in order to adjust the speed ofrotation of the chute 32 to the desired value N. By means of thevariable speed drive 106, the control unit 102 sets the tilting speed ofthe chute 3. In order to reduce the tilt of the chute 32 with respect tothe vertical, the variable speed drive 104 operates the electric motor60 so that it drives the suspension rotor 18 at speed N in the directionof the arrow 120′, and the variable speed drive 106 operates theelectric motor 80 as a generator which imposes a braking moment to thetilt controlling rotor 28. By means of the variable speed drive 106, thecontrol unit 102 sets the braking moment of the tilt controlling rotor28 in order to adjust the tilting speed of the chute 32 to the desiredvalue. By means of the variable speed drive 104, the control unit 102sets the speed of rotation of the suspension rotor 18 to the value N.

Upon its assembly or during maintenance work, the angle sensor 110 mustbe reset, i.e. an initial count value must be associated with awell-defined angle of inclination of the chute 32. With reference toFIG. 3, it is seen that the suspension mechanism 36′ is equipped with anangle abutment 120 and with a lever 122 interdependent with thesuspension pin 40′. To reset the angle sensor 110, the tilt rotor 28 isdriven by means of motor 80 in order to have the lever 122 abut againstthe angle abutment 120.

In the embodiment of FIG. 4, a differential angle sensor 126 is usedwhich directly senses the angular position relatively to both rotors 18and 28. This differential angle sensor 126 is mounted in parallel on theclutch 90. If the device does not comprise a clutch 90 because thetilting mechanism of the chute is perfectly self-blocking, then thedifferential angle sensor 126 may take the place of the clutch 90, so asto be directly connected between both shafts 56 and 76. Considering thatthe casing of the differential angle sensor 126 is also rotating, awireless transmission of measurements towards a receiver 128 which isrotationally fixed, is provided advantageously.

In the embodiment of FIG. 5, a differential measurement mechanism 130 isused, which is connected in parallel on the clutch 90. This mechanismcomprises a first input shaft 132, a second input shaft 134 and anoutput shaft 136. The first input shaft is rotated by the output shaft56 of the casing 50. It consequently senses the angular position of thesuspension rotor 18. The second input shaft is rotated by the inputshaft 76 of the casing 70. It consequently senses the angular positionof the tilt controlling rotor 28. This differential measurementmechanism 130 additionally comprises a system of planetary gearsdimensioned in order that the output shaft 136 is rotationally fixedwhen both rotors 18, 28 have the same speed of rotation, so that itreproduces the angle of inclination of the chute 32 in a rotationallyfixed reference system.

FIG. 6 shows a planar view of this planetary gear system. A horizontalannular toothed wheel 138 is seen, which engages on its externalperimeter with a pinion 140 of the first input shaft 132; a solar wheel142 which is borne by the second input shaft 134; two satellite pinions144 which engage with the internal perimeter of the annular toothedwheel 138 and the solar wheel 142; and a satellite pinion support 146,with which is coupled the output shaft 136. A single angular sensor 148then senses the angular position of the output shaft 136 and therebydetects the tilt of the chute in a rotationally fixed reference system.

1. A device for distributing bulk materials comprising: a support frame;a distribution chute for the bulk materials; a suspension rotor mountedin said support frame so as to be capable of rotating about asubstantially vertical axis of rotation, said chute being suspended tosaid suspension rotor so as to be tiltable about a substantiallyhorizontal tilt axis; a first motor able to rotate said suspension rotorabout its axis of rotation in a first direction; a tilt controllingrotor mounted in said support frame so that it is capable of rotatingabout a substantially vertical axis of rotation; and a tilting mechanismconnected between said chute and said tilt controlling rotor, saidtilting mechanism being designed in order to transform a differentialrotation of said suspension rotor and of said tilt controlling rotorinto a variation of the angle of inclination of said chute between twoextreme positions, wherein said chute is balanced so that it returns toa first of said two extreme positions, while accelerating said tiltcontrolling rotor via said tilting mechanism in the direction ofrotation of said suspension rotor; a first braking device associatedwith said tilt controlling rotor so that it is capable of exerting abraking moment on said tilt controlling rotor; and a first controldevice associated with said first braking device in order to control thevariation of the angle of inclination of said chute by controlledbraking of said tilt controlling rotor.
 2. The device according to claim1, further comprising: a transmission mechanism including a clutch whichis connected between said suspension rotor and said tilt controllingrotor, so that in an engaged position of said clutch, said mechanismmakes both rotors interdependent in rotation while providing equalspeeds of rotation for both rotors.
 3. The device according to claim 1,further comprising: a second motor which is associated with said tiltcontrolling rotor so that it is capable of driving the latter about itsaxis of rotation in a second direction of rotation, opposite to saidfirst direction of rotation; a second braking device which is associatedwith said suspension rotor so that it is capable of exerting a brakingmoment on said suspension rotor.
 4. The device according to claim 3,further comprising: a second control device which is associated withsaid second braking device, in order to control the variation of theangle of inclination of said chute rotating in said second direction byvarying the braking moment of said suspension rotor.
 5. The deviceaccording to claim 4, further comprising: a variable speed driveassociated with said second motor; and a control device associated withsaid variable speed drive in order to control the speed of rotation ofsaid suspension rotor, by varying the speed of rotation of said tiltcontrolling rotor.
 6. The device according to claim 3, furthercomprising: a variable speed drive associated with said second motor;and a control device associated with said variable speed drive in orderto control the speed of tilting of said chute by varying the speed ofrotation of said tilt controlling rotor with the speed of rotation ofsaid suspension rotor being kept constant.
 7. The device according toclaim 3, wherein: said first motor and said second braking device, saidsecond motor and said first braking device, respectively, form a unitcomprising a rotating electric machine powered by an electrical circuitso that it is capable of operating in motor mode, developing a drivingtorque, and capable of operating in generator mode, developing a brakingtorque in at least one direction of rotation.
 8. The device according toclaim 7, wherein: said electric rotating machine is an electric motorequipped with a speed reducer, and said electric circuit is a staticfrequency converter.
 9. The device according to claim 1, wherein saidfirst control device, said second control device, respectively,comprises: a first angle sensor sensing the angular position of saidsuspension rotor; a second angle sensor sensing the angular position ofsaid tilt controlling rotor; and computation means for computing therelative angular position of both rotors.
 10. The device according toclaim 1, wherein said first control device, said second control device,respectively, comprises: a differential angle sensor sensing the angularposition of both rotors.
 11. The device according to claim 1, whereinsaid first control device, said second control device, respectively,comprises: a differential measurement mechanism, with a first inputshaft, a second input shaft and an output shaft, said first input shaftbeing rotated by said suspension rotor, said second input shaft beingrotated by said tilt controlling rotor, and said differentialmeasurement mechanism being dimensioned so that said output shaft isrotationally fixed when both rotors have the same speed of rotation; andan angle sensor sensing the angular position of said output shaft.
 12. Adevice for distributing bulk materials comprising: a support frame; adistribution chute for the bulks materials; a suspension rotor mountedin said support frame so that it is capable of rotating about asubstantially vertical axis of rotation, said chute being suspended tosaid suspension rotor so as to be tiltable about a substantiallyhorizontal tilt axis; a first motor able to rotate said suspension rotorabout its axis of rotation in a first direction; a tilt controllingrotor mounted in said support frame so that it is capable of rotatingabout a substantially vertical axis of rotation; and a tilting mechanismconnected between said chute and said tilt controlling rotor, saidtilting mechanism being designed so as to transform a differentialrotation of said suspension rotor and said tilt controlling rotor into avariation of the angle of inclination of said chute between two extremepositions; a first braking device associated with said tilt controllingrotor so that it is capable of exerting a braking moment on said tiltcontrolling rotor; a second motor associated with said tilt controllingrotor so that it is capable of driving the latter about its axis ofrotation in said first direction at a higher speed of rotation than thedesired speed of rotation for said chute; a second braking deviceassociated with said suspension rotor so that it is capable of exertinga braking moment on said suspension rotor; and a control device cable ofcontrolling the tilting of said chute: a) in a first direction, bydriving said suspension rotor in said first direction and by braking ofsaid tilt controlling rotor in a controlled manner by means of saidfirst braking device, and b) in a second direction, by driving said tiltcontrolling rotor in said first direction at a higher speed of rotationthan the desired speed of rotation for said chute and by braking of saidsuspension rotor in a controlled manner by means of said second brakingdevice.
 13. A device for distributing bulk materials comprising: Thedevice according to claim 12, wherein said tilting mechanism is aself-blocking mechanism.
 14. The device according to claim 12, furthercomprising: a transmission mechanism with a clutch which is connectedbetween said suspension rotor and said tilt controlling rotor, so thatin the engaged position of said clutch, said mechanism makes both rotorsinterdependent in rotation by providing equal speeds of rotation forboth rotors.
 15. The device according to claim 12, wherein: said firstmotor is able to drive said suspension rotor in a second direction ofrotation opposite to said first direction of rotation, at the desiredspeed of rotation for said chute; and said second motor is able to drivesaid tilt controlling rotor in a second direction of rotation, at ahigher speed of rotation than the desired speed of rotation for saidchute.
 16. The device according to claim 13, wherein, upon a rotation ofsaid chute in said second direction, said control device associated withsaid first braking device, with said second braking device and with saidsecond motor, is capable of controlling the tilting of said chute: (a)in a first direction, by driving said tilt controlling rotor by means ofsaid second motor in said second direction with a higher speed ofrotation than the desired speed of rotation for said chute and bybraking of said suspension rotor in a controlled manner by means of saidsecond braking device; and (b) in a second direction, by driving saidsuspension rotor in said second direction and by braking of said tiltcontrolling rotor in a controlled manner by means of said first brakingdevice.
 17. The device according to claim 12, wherein: a variable speeddrive is associated with said second motor; and said control device isable to control said variable speed drive in order to control the speedof rotation of said suspension rotor, by varying the speed of rotationof said tilt controlling rotor.
 18. The device according to claim 12,wherein: a variable speed drive is associated with said second motor;and said control device is able to control said variable speed drive inorder to control the tilting speed of said chute by varying the speed ofrotation of said tilt controlling rotor.
 19. The device according toclaim 12, wherein said first motor and said second braking device, saidsecond motor and said first braking device respectively, form a unitcomprising a rotating electric machine powered by an electrical circuitso that said unit is capable of operating in motor mode, developing adriving torque, and in generator mode developing a braking torque, in atleast one direction of rotation.
 20. The device according to claim 19,wherein: said rotating electric machine is an electric motor equippedwith a speed reducer, and said electrical circuit is a static frequencyconverter allowing operation of said rotating electric machine in fourquadrants of the speed of rotation/developed torque diagram.
 21. Thedevice according to claim 12, wherein said control device comprises: afirst angle sensor sensing the angular position of said suspensionrotor; a second angle sensor sensing the angular position of said tiltcontrolling rotor; and computation means for computing the relativeangular position of both rotors.
 22. The device according to claim 12,wherein said control device comprises: a differential angle sensorsensing the relative angular position of both rotors.
 23. The deviceaccording to claim 12, wherein said control device comprises: adifferential measurement mechanism with a first input shaft, a secondinput shaft and an output shaft, said first input shaft being rotated bysaid suspension rotor, said second input shaft being rotated by saidtilt controlling rotor, and said differential measurement mechanismbeing dimensioned so that said output shaft is rotationally fixed whenboth rotors have the same speed of rotation; and an angle sensor sensingthe angular position of said output shaft.
 24. The device according toclaim 12, wherein said control device comprises: an inclination sensorfor said chute rotating with said chute, a transmitter associated withsaid inclination sensor and at least one receiver mounted fixedly inrotation in said support frame.